The US is preparing to curtail Chinese companies’ access to cloud computing services including Amazon.com Inc.’s and Microsoft Corp.’s, the Wall Street Journal reported, citing people familiar with the situation.

Washington is considering requiring cloud providers to seek government permission before serving Chinese firms that employ such platforms to train AI models, the Journal reported. Microsoft Azure and Amazon Web Services are the global leaders in the business of providing internet computing to enterprises, and compete in China with the likes of Alibaba Group Holding Ltd. through local, state-affiliated datacenter partners.

The Biden administration plans to tighten export controls announced in October to restrict sales of some artificial-intelligence chips to China, seeking to contain its rival’s development of a technology considered key to the country’s geopolitical and economic future. Part of the measures under discussion included restricting cloud access for Chinese AI developers, which was first reported by the Journal last week.

Under the broader Commerce Department proposal, expected in July, the US would revise export controls to make it harder to sell some chips to China without a license. The move is aimed in part at Nvidia Corp.’s A800 chip, which the US-based company designed after the earlier controls were announced. The product’s configuration comes just within those limits.

The US and China are escalating their technological conflict. On Monday, Beijing slapped controls on the export of metals critical to the chip, EV and defense industries, showing it has some power to retaliate against moves by the US, Japan and Europe to cut Beijing off from advanced technology.

Read more: Xi’s Metal Curbs Could Backfire as G-7 Seeks China Alternative